Known guide bars of the kind described above have a three-layer assembly and are disclosed in U.S. Pat. No. 4,693,007 and 4,903,410. Accordingly, these guide bars include two side parts and a center part arranged between the side parts. The center part supports the side parts with respect to each other and defines a spacer which fixes the spacing which corresponds to the width of the guide groove. The guide bar is made as light as possible but yet is nonetheless configured to be stable with respect to bending and torsion loads. This is achieved by configuring the center part as a frame which is filled with plastic as disclosed in U.S. Pat. No. 4,693,007. The two side parts can be configured as frames as disclosed in U.S. Pat. No. 4,903,410. However, in each case, a three-layer assembly is provided in all lamellar guide bars; that is, the center part is required.